Sunday, November 2, 2014

Slipper snails brood their offspring. They produce eggs enclosed in transparent capsules and they keep these covered by the shell. The scientific literature is full of statements that they "brood in the mantle cavity". This is not accurate.What is the mantle cavity?The mantle is characteristic of molluscs and is basically a skirt of tissue formed by the dorsal body wall that covers the visceral mass. In squid it is the part that is used as squid rings. In clams and snails it is the tissue that underlies the shell.

Head-on view of a Crepidula

The mantle cavity is defined as the space enclosed by the mantle and includes the gills, anus, osphradium and gonopores. In slipper snails this space is large, to contain the extensive gills needed for filter feeding. It extends from the front margin of the shell, over the head, and gradually tapers all the way to the posterior end. Slipper snails do not brood their egg capsules in this space.

Crepidula atrasolea brooding. The eggs are orange andcan be seen through the plastic the snail has attached to

Where do slipper snails keep their eggs?In the CollinLab we keep slipper snails in plastic cups. In this way we can see when they produce eggs and we can collect the embryos or larvae at the age or stage we need. Looking a the snails in this way it is very clear that the egg capsules are deposited under the snail, not above the head in the mantle cavity, but below the head. The mother attaches the stalks of the capsules to the substrate beneath her neck. As far as we know there is not formal anatomical name for this space. In publications we say that slipper snails brood the egg capsules "between the substrate, the neck and the propodium".

Head-on view showing the location of the eggs relative to the mantle cavity

Tuesday, February 11, 2014

The second floor of the Naos Laboratories is packed to the
ceiling with high-tech DNA sequencing equipment: precision incubators, heatblocks, PCR machines for replicating DNA molecules,
robots for processing samples and DNA sequencing machines.

It’s a different story up on the third floor.You’d be surprised at what things ecologists bring in from home to use in the lab.Here are a few of the items we use in the
CollinLab:

Nail polish is great for marking individual snails. We want to follow snails in the intertidal to see if they return every day to the same pool or crevice. Now that you can get so many colors it's perfect to just dab a bit of polish on each snail.

20 years ago it was all shades of red and pink, but now the snails can really shine. …. and yes, certain snails look better in certain colors.

A yogurt makerhas
been used in the lab to test the tolerance of Nerita egg capsules to high temperatures. Aquarium heaters have a built-in shut-off before they reach temperatures experienced in tropical tide pools. The yogurt maker hits the exact temperature.

Custard dishes. We buy these by the case to use for larval rearing experiments. They fit perfectly under the microscope.

It's not just the CollinLab that gets creative.In fact, we are rather tame in our
choices compared to some famous marine biology researchers. My favorite examples include:

In a flamboyant landmark study Mimi Koehl and Tom Powell threw pounds of glitter, poppy seeds and snapdragon seeds off the rocks of the Washington coast.They wanted to understand how waves disperse small particles away from the intertidal. The glitter and seeds were
used to model different kinds of marine invertebrate eggs (some eggs are buoyant
and some sink).So they released
thousands of these "artificial" eggs at one time and used fluorescein to label the sea water. A team of students and helpers scooped up
samples of water along the coast to track the movement of the different particles to see if they all traveled in the same way with the water.

In a another important but quirky study, researchers working at
the Bocas del Toro Research Station tied tampons to corals. They wanted to understand the causative agents of coral disease.Davey Kline and Steve Vollmer extracted
different microbes from infected areas of coral tissues. To find out which of these cause the disease, which are benign, and which are secondary infections that do
not transmit the disease, they needed to expose corals
to the different isolated microbes.They searched the small town of Bocas del Toro for materials that could
be used to absorb the different solutions and tied to the corals
to expose an area of health tissue to the potential
pathogens. Tampons turned out to be perfect! The experiment was a success and was published in Nature-Scientific Reports.

Let us know if you have used art, kitchen, or personal
supplies for unusual scientific purposes.

Thursday, November 14, 2013

As a side project in the lab we have been making snail porn (here for full YouTube video). Trying to get photos or videos of
our snails in the act, doing the deed, getting it on... or as we say in lab, copulating or mating.The last post described how to tell the sex of slipper
snails. Just like lots of animals males
have a penis and females have an opening that receives the penis and the
sperm. But, something we would like to
know is how exactly does this transfer happen?

The snails are shy and seeing what's going on is easier said
than done.

You can see the penis from the male Crepidula fornicata extending under the shell of the female he is stacked on.

The common idea that slipper snails have to be stacked one on top of the other to mate is not always true.This small Crepidula onyx is extending his penis across the substrate to the female.

From observations of snails in cups like these we know that mating can
last for hours. Snails are slow, but what is going
on under there for all that time?
Recently Matt Starr, a student in the lab, was lucky enough to get this footage of mating in a pair of snails that
had been detached from the substrate.

Here the male is just exploring, prior to copulation.

To most people it probably seems that as long as mating
happens and successfully produces offspring it's not really important exactly
how. But the details of copulation can
shed light on some important questions in evolutionary biology and behavioral
research. For example: Can females control who they mate with? Why do females mate more often than necessary to fertilize
their eggs?

If they mate with more than one male, can females manipulate
whose sperm they use to fertilize their eggs?

Copulation!

We already knew, from anatomy that sperm is passed to the
female in an open groove that runs to the end of the penis. Unfortunately we can't see the sperm moving
in the videos.

But we can see that there
is a lot of activity on the part of both the male and female. We can see is that the long thin papilla at
the end of the penis inserts into the female genital papilla. That's not so surprising, but makes us wonder
what happens in the many species that lack both the female genital papilla as
well as thin extension of the penis.

So far Crepidula
incurvais the only species for which we've obtained video. We hope to find out how copulation differs
across species with different penis morphologies and why mating takes so
long. In some animals the male uses his
penis to displace sperm that were deposited by previous males, could this be
what's taking so long when Crepidula
mate?

About Us

Research in the Collin Lab focuses on the evolution of life histories and development of marine invertebrates. Our current work uses marine slipper limpets (Calyptraeidae) to try to understand the evolutionary loss and possible reacquisition of feeding larvae.
The Collin Lab is located in Panama City, Panama, at the Smithsonian Tropical Research Institute's Naos Marine Laboratories, but our field work takes us to various other countries in the Americas.
Using our blog we hope to give you an introduction to the faces in the Collin Lab, as well as a taste of the kinds of projects we are working on and the adventures we have while doing them.
http://www.stri.si.edu/
http://www.stri.si.edu/sites/collinlab/
Some of this material is based upon work supported by the National Science Foundation under Grant Number (IOS 1019727). Any opinions, findings, and conclusions or recommendations expressed in this material are those of the author(s) and do not necessarily reflect the views of the National Science Foundation.